How can I normalize 3 foto same way?

[nikaan]

I have a 3 foto - R, G, and B component from one file.

But before combine them I need normalize.
If I normilize them one after another than they merge rougtness.
How can I normalize all foto same scale?

[fmw42]

Merge them into one RGB image. Then use -level or try my script autolevel. See

http://www.imagemagick.org/Usage/color/#levels
http://www.fmwconcepts.com/imagemagick/index.php

[nikaan]

thank you.